package leetcode101.mathematical_problem;

import java.util.Arrays;

/**
 * @author Synhard
 * @version 1.0
 * @Class Code7
 * @Description 384. 打乱数组
 * 给你一个整数数组 nums ，设计算法来打乱一个没有重复元素的数组。
 *
 * 实现 Solution class:
 *
 * Solution(int[] nums) 使用整数数组 nums 初始化对象
 * int[] reset() 重设数组到它的初始状态并返回
 * int[] shuffle() 返回数组随机打乱后的结果
 *  
 *
 * 示例：
 *
 * 输入
 * ["Solution", "shuffle", "reset", "shuffle"]
 * [[[1, 2, 3]], [], [], []]
 * 输出
 * [null, [3, 1, 2], [1, 2, 3], [1, 3, 2]]
 *
 * 解释
 * Solution solution = new Solution([1, 2, 3]);
 * solution.shuffle();    // 打乱数组 [1,2,3] 并返回结果。任何 [1,2,3]的排列返回的概率应该相同。例如，返回 [3, 1, 2]
 * solution.reset();      // 重设数组到它的初始状态 [1, 2, 3] 。返回 [1, 2, 3]
 * solution.shuffle();    // 随机返回数组 [1, 2, 3] 打乱后的结果。例如，返回 [1, 3, 2]
 *
 * @tel 13001321080
 * @email 823436512@qq.com
 * @date 2021-04-25 9:45
 */
public class Code7 {
    public static void main(String[] args) {
        int[] arr = new int[] {1, 2, 3, 4};
        Solution s = new Solution(arr);
        System.out.println(Arrays.toString(s.reset()));
        System.out.println(Arrays.toString(s.shuffle()));
        System.out.println(Arrays.toString(s.shuffle()));
        System.out.println(Arrays.toString(s.reset()));
    }

    static class Solution {

        private int[] nums;
        private int[] origin;

        public Solution(int[] nums) {
            this.nums = nums;
            this.origin = nums.clone();
        }

        /** Resets the array to its original configuration and return it. */
        public int[] reset() {
            return origin;
        }

        /** Returns a random shuffling of the array. */
        public int[] shuffle() {
            for (int i = 0; i < nums.length; i++) {
                int random = (int) (Math.random() * (nums.length - 1));
                swap(i, random);
            }
            return nums;
        }

        public void swap(int pos1, int pos2) {
            int temp = nums[pos1];
            nums[pos1] = nums[pos2];
            nums[pos2] = temp;
        }
    }
}

